Crosslinked alkylated styrene polymers are well known organic liquid absorbents. U.S. Pat. No. 3,520,806 teaches that polymers of tert-butylstyrene or copolymers of tert-butylstyrene and methyl methacrylate crosslinked with divinylbenzene are effective absorbents for organic liquids such as benzene, hexane, kerosene, and toluene. Crosslinking is needed to prevent the polymers from dissolving in the organic liquid. The polymers are prepared by emulsion, suspension, or bulk polymerization.
Unfortunately, the absorption capacity of these polymers is limited, and absorption rates possible are still somewhat less satisfactory than would be desirable. Previous efforts to optimize these properties have focused on varying the crosslink density or the type of monomers employed. Incorporation of other monomers has yielded only limited improvement in absorption capacity or rate. Controlling absorptivity via crosslink density is difficult because there is a narrow processing window: Too little crosslinking agent gives oil-soluble polymers, while too much crosslinker reduces the polymer's ability to absorb organic liquids.
Interpolymers of polyolefins and styrenic monomers are disclosed in European Patent Application No. 397,001. These polymers are useful for producing expanded plastic articles having good elasticity. A crosslinking agent is used in an amount within the range of about 0.005 to 0.05 mole percent based on the amount of styrenic monomer. The low degree of crosslinking makes these polymer beads capable of impregnation and expansion to form low-density foamed articles. The polymers described in this reference would not be useful as oil absorbents because they are soluble in organic liquids.
An object of the invention is to provide improved oil-absorbent compositions. Oil-insoluble compositions with high capacities and fast absorption rates are desirable. Preferably, the compositions have effective oil-absorption properties over a wide range of processing conditions.